Very-high-bit-rate digital subscriber line (“VDSL”) service is currently one of the highest speed digital subscriber line (“DSL”) services, with asymmetric rates up to 50 Mb/s downstream and 6.4 Mb/s upstream. However, to sustain VDSL service, VDSL loops are typically very short such that optical fiber may be used for all but the least few thousand feet. Due to the increasing popularity of VDSL service due to its higher bit rates, it is desirable to have an accurate and efficient method for testing of potential VDSL lines.